Gubbels Ed J, Scholten Janneke, Janss Luc, Rothuizen Jan
Genetic Counselling Services, Eijkerstraat 42, 6269 BN Margraten, The Netherlands.
Anim Reprod Sci. 2009 Jul;113(1-4):187-95. doi: 10.1016/j.anireprosci.2008.07.004. Epub 2008 Jul 8.
The aim of this study was to identify the influence of genetic carriership for cryptorchidism on litter sizes and sex ratios in the offspring. Weaning data of 11,230 litters in 12 purebred dog breeds were evaluated. Parents were classified as cryptorchidism 'carriers' (C) when at least one of their offspring was found cryptorchid. Subsequently the effects of 'carrier' and 'non-carrier' (NC) parents on their litters were studied. In litters from C x C parents we found an increased number of males per litter in all breeds, a reduced number of females per litter in 8 breeds and an increased litter size in 11 breeds in comparison with litters from NC x NC parents. Over all breeds the effects on litter size, on number of males per litter and on sex ratio were highly significant. Mixed litters from C x NC and NC x C did not show these effects and were not significantly different from the NC x NC offspring. Our results suggest a general mechanism in the dog species which causes cryptorchidism as well as increased male/female ratios and increased litter sizes. A consequence of such a mechanism is that selection in favor of increasing reproduction output frustrates selective efforts to eliminate cryptorchidism.
本研究的目的是确定隐睾症基因携带者对后代窝产仔数和性别比例的影响。我们评估了12个纯种犬种中11230窝的断奶数据。当父母至少有一个后代被发现患有隐睾症时，其被归类为隐睾症“携带者”（C）。随后，研究了“携带者”和“非携带者”（NC）父母对其窝产仔的影响。与NC×NC父母的窝产仔相比，我们发现C×C父母的窝产仔中，所有犬种每窝雄性数量增加，8个犬种每窝雌性数量减少，11个犬种窝产仔数增加。在所有犬种中，对窝产仔数、每窝雄性数量和性别比例的影响非常显著。C×NC和NC×C的混合窝产仔未显示出这些影响，且与NC×NC后代无显著差异。我们的结果表明，犬种中存在一种普遍机制，该机制导致隐睾症以及雄性/雌性比例增加和窝产仔数增加。这种机制的一个后果是，有利于提高繁殖产量的选择会阻碍消除隐睾症的选择性努力。
